Drawing sheet glass



Aug. 16, 1927. 1,639,452

J. L. DRAKE DRAWING SHEET GLAS 5 Filed May 15. 1924 2 Sheets-Sheet l INVE NT [1 R 1755/7 Z. flra/e BY Q1 ATT RNEY.

16 -1 2 Aug 9 7 J. DRAKE DRAWING SHEET GLASS 2 Shuts-Sheet 2 Filed May 15. 1924 II I\- INVENTEIH- JOhn Lflrae *ATT RNEY.

Patented Aug. 16, 1927.

UNITED STATES anna PATENT OFFICE.

JOHN L. DRAKE, OF CHARLESTON, WEST VIRGINIA, ASSIGNOR TO THE LIBBEY- O'WIEINS SHEET GLASS COMPANY, OF TOLEDO, OHIO, A CORIPORA'IION OF OHIO.

DRAWING SHEET GLASS.

Application filed 'May 15,

This invention relates to the art of drawing sheet glass, and more particularly to an improved process and apparatus for main.- taining the width of the sheet and imparting lateral tension to the sheet during the sheet forming period.

away through suitable drawing and flattening mechanism into the leer. A pair of small edge-forming rollers grip each sheet edge at its source. lhese rollers are positively driven at a peripheral speed considerably less than the speed at which the glass is drawn about the bending roller. Thus v these edge rollers function not only to positively feed glass upwardly from the molten pool into the edges of the sheet, but alsov hold back on the edge portions of the vertical run of the sheet so as to establish a stretching tension therein. In this way the rollers function, in cooperation with the bending roll, to hold the sheet to a substantially constant width, and counteract the sheets natural tendency to narrow away at its source. It will be noted however, that there is no positive means exerting lateral tension on any portion of the vertical run of the sheet between the sheet source and the bending roller, and the sheet due to its natural tendency to contract when cooling, and also due to the longitudinal elongation to which it is subjected during this period, he comes several inches narrower at the bending roller than it is at its source. It is also believed that the absence of lateral tension in the sheet during this period is one cause of certain waves or inequalities in sheet thickness sometimes present in the drawn sheet.

According to the present invention a second pair of edge-gripping rollers are ositioned in engagement with the edge 0 the sheet at a point in its vertical run intermediate the source and the bending member. These rollers are positively driven at a 1924. Serial No. 713,390.

speed intermediate that of the edge forming rollers and the bending roller, that is their peripheral speed is faster than that of the edge-forming rollers, but slower than that of the bending roller or the sheet drawing means, In this way a longitudinal tension is maintained in that portion of the sheet edge between the two pairs of edge-gripping rollers, and at the same time longitudinal tension is maintained between the intermediate edge-gripping rollers and the bending roller. Due to these variations in sheet engaging speeds, and the longitudinal sheet tension resulting therefrom, the sheet may be continuously held between the upper pairs of rollers and forced to follow a more nearly vertical path than is the case when these auxiliary rollers are not used. In other words, the tendency for the sheet to contract immediately above the edge-forming rollers is resisted to such an extent that the finished sheet will be several inches wider than was formerly the case, and at I the same time the sheet during its formative period will be subjected to a continuous lateral stress through the zone immediately above its source, thus'tending to eliminate waves or other inequalities that might result from the lack of adequate lateral tension.

The objects and advantages of the invention will be better understood from the following detailed description of one approved form of the apparatus.

In the accompanying drawings:

Fig. 1 is a transverse vertical section through the receptacle containing the pool of molten glass, the sheet edge drawing and bending members being shown in elevation.

Fig. 2 is a similar elevation, on an en larged scale, of one set of edge-forming and stretching members.

Fig. 3 is an end elevation of the mechanism shown in Fig. 2.

Fig. 4 is a plan view of one of the upper setsef edgegripping rollers and the supporting and driving mechanism therefor.

Fig. 5 is an enlarged elevation of the driving gears whereby the two sets of rollers are driven simultaneously at the desired speed.

This View is taken substantially on the line illustrating diagrammatically the relative v positions of the sheet-drawing, bending and the molten source 2.

Gripping each edge of the sheet 1 at its source 18 a pair of driven rollers 7 usually rovided with a roughened or knurled surface to insure a positive grip upon the molten glass passing therebetween. These rollers 7 are mounted on the inner ends of suitable I yotary shafts 8. The auxiliary edge-drawing rollers 9, forming the particular subjectmatter of the present invention, may have substantially the same form as rollers 7 and are mounted at the inner ends of shafts 10 similar in all respects to the'shafts 8. The supporting and driving means for each pair of shafts 8 and ,10, at either side of the sheet, are substantially identical, and

a description of one will suflice for all. One

of. each air of shafts 8 or 10 is journaled in a fixe bearing bracket 11- carried by or formed on a sup orting plate 12. The other shaft 8 or 10 of the pair is journaled in a similar bearing 13 pivoted as at 14 in the supporting plate 12 so that the roller 7 or 9 carried thereby may be swung toward or from its companion roller. A spring 15 whose compression :is adjustable by means of screw 16 is mounted between the bearings 11 v and 13 so as to normally force the pair of rollers 7 or 9 toward one another. A handle 17 secured to the side of the movable hearing 13 forms a convenient means for swinging the movable roller away from its com; panion roller to enable the sheet to be engaged therebetween. When the handle 17 is released, the spring 15 will force the two rollers toward one another in yielding contact with the sheet edge. The supporting plate 12 is provided'with a flange 18 at one edge engaging a complementary recess in a supporting frame 19 carried by stationary beam 20 at the side of the machlne. Clamping screws 21 extending through the opposite side of frame 19 engage the opposite edge 22 of plate 12 to hold the same in any desired fixed position. By loosening the screws 21 the roller assembly Ina be moved in or out with relation to the e ge of glass sheet 1.

A continuous flow of water or other cooling fluid passes in through pipe 23, which extends inwardly through pipe 8 to the inlower end on the pair of shafts 8.

terior of the roller 7, this water then flowing back through pipe 8 and around pipe 23, and out through the exit pipe 24. In this way the roller 7 and pipe'8 are continuously.

filled with a constantly renewed supply of cooling fluid. This protects the roller and shaft from the intense heat to which they are subjected, and at the same time exerts a cooling action on the edge portions of the sheet which assists in the sheet formation. It will be understood that each of the shafts 8 and 10 and rollers 7 and 9 is provided with a similar individual cooling system. 7

A bevel gear 25 secured to one shaft 8 meshes with and is driven by a similar bevel gear 26 on a stub-shaft 27 driven through universal joint 28 from a drive shaft 29. A pair of similar intermeshing spur gears 30,

one secured to each shaft 8, serve to drive the two shafts and the rollers 7 at the same speed but in opposite directions. A spur gear 31 secured to one of the shafts 8 meshes with an intermediate spur gear 32, which in turn meshes with a gear- 33 secured to one of the shafts 10. Intermediate gear 32 is carried. in a frame 34 supported. at its The bearing 35 for one of the shafts 8 is slidable in slots 36 in the main body portion of frame 34 and permits shafts 8 to be moved toward or from one another in adjusting the position of roller 7. A pair of intermeshing spur' ears 37, one of which is secured to each sha t 10 serve to drive the two shafts 10 at thesame speed but in opposite directions. The proportions of several gears 31, 32 and 33 will be so designed that shafts 10 will be rotated at a somewhat greater speed than shafts 8. In this way the peripheral speed of the upper pair of rollers 9 will be reater than the peripheral speed of the Tower edge-forming rollers 7.

In the normal operation of sheet drawing machines of this type, as disclosed in the Colburn patent referred to hereinabove, the edge-forming rollers 7 are driven at a considerably slower peripheral speed than the linear speed imparted to the body of the sheet as a whole by the main drawing means 6. In this way the positively driven rollers 7 feed molten glass up into the sheet edges from molten pool 2 at a rather slow rate, and subsequently this edge glass is stretched or elongated uring its vertical passage up to the bending roll 4 until the edge portions of the sheet have reached the speed imparted to the entire sheet body by the drawing mechanism 6. In this way the final width of the continuous sheet is maintained practically constant, but the sheet narrows up considerably in its passage from edge-forming rollers? to bending roll 4 as indicated by the dotted lines 38 in Fig. 1.

When the supplemental edge-drawing rollers 9 are used the still plastic sheet is stretched out by means of hooks or other suitable tools until it engages between the driven rollers 9. Since these rollers 9 are driven at a greater speed than rollers 7 a longitudinal tension or drawing force will be exerted on that portion of the sheet edge between the rollers 7 and 9 and the sheetwill remain in engagement with both pair of rollers. At the same time since roller-s 9 are driven slower than the drawing n'iechanism 6, there will also be a stretching tension between the rollers 9 and the bending roller 4. It has been discovered that as a result of this drawing operation, the glass sheet 1 will maintain a practically constant width from its source up to the bending roller 4, at which point it has become set to such an extent that there is very little further lateral contraction. At the same time the additional lateral tension imparted to the sheet during its formative period tends to eliminate the waves or other surface inequalities which otherwise might be present in the sheet.

It has been noted that when the additional edge-rollers 9 are used, the meniscus 39, or mass of glass drawn up fromthe molten pool at the sheet source is thicker and rises to a greater height than was previously the case. Thus is some manner, these auxiliary rollers function to actually draw a greater amount of glass up into the sheet, and do not merely stretch to a greater width the mass of glass drawn upby'the drawin mechanism 6 and edge-rollers 7 although the sheet is at the same time subjected to a greater lateral tension than was previously the case.

The distance of rollers 9 above rollers 7 may be varied, but should not be sutiicient to bring the rollers 9 outside of the initial forming zone of the sheet. The sheet 1 should still remain sufliciently plastic to be positively engaged by the knurled surface of rollers 9.

The rollers 7 and 9 need not necessarily be constructed of the exact cylindrical torm shown in Figs. 1, 2 and 4 although this form has been operated successfully. The lower rollers may be shaped as shown at 40 in Fig. 7, so as to form a thicker edge or head on the sheet. The upper rolle s may also be given this configuration, or it cylindrical as at 9, will have a thicker mass of plastic glass to engage, thus insuring a more posit ivegrip on the sheet. Many other forms of sheetgri ping surfaces might be given to these r01 ers without departing from the principles of this invention.

Claims:

1. In the art of drawing shoot glass from a mass of molten glass, the method consist ing in applying longitudinal drawing forces to the sheet edges only at the sheet source. applying supplemental drawing forces to the sheet edges only at a greater drawing speed at points beyond the sheet source, and subsequently applying a still faster drawing force to the entire body of the sheet.

2.111 an apparatus for drawing sheet glass, a plurality of pairs of edge-gripping rollers engaging each edge of the sheet. and means for simultaneously driving the pairs of rollers at different speeds, the rollers most remote from the sheet source having the greatest speed.

3. In an apparatus for drawing sheet glass, a container for a sup )ly of molten glass from which the sheet is drawn, a bend ing' roller about which the. plastic sheet is detlectecha pair of edge-forming rollers engaging each sheet edge at its source. the edge rollers being driven at a peripheral speed less than that of the bending roller, pairs of edge rollers engaging the sheet edge between the edge-forming rollers and the bending roller and means for positively driving these intermediate rollers at a pe-- ripheral speed greater than that of the edgetorining rollers but less than that of the bending roller.

4. In sheet glass apparatus, means for drawing a sheet from a mass of molten glass. a plurality of pairs of edge gripping rollers engaging each edge of the sheet, the pairs of rollers at each edge being rotated at different relative speeds, while the corresponding rollers in each pair are driven at substantially the same speed.

5. In sheet glass apparatus, means tor drawing a sheet from a mass of molten glass. pairs of rolls. arranged at each edge of the sheet and engaging the same. and means for driving the pairs of rolls at different speeds,

the corresponding rolls in each pair being driven at the same speed.

6. In sheet glass apparatus, means for drawing a sheet from a mass of molten glass, pairs of rolls arranged at each edge of the sheet and engaging the same, and means for retarding the pairs of rolls in a manner that their peripheral speeds will be different. the peripheral speed of corresponding rolls in each pair. being the same. v r

7. In sheet glass apparatus, means for dran ing a sheet from a mass of molten glass, pairs of rolls arranged at each edge of the sheet and enga ing the same, means for retarding the pairs of rolls in a manner that their peripheral speeds will be different, the peripheral speed of corresponding rolls in each pair being the same, and means for controlling the temperature of the rolls.

8. In sheet glass apparatus means for drawing a sheet from a mass of molten glass, airs of rolls arranged at each edge of the sheet and engaging the same, the lower pair of rolls being arranged at the formative portion of the edge, and the upper air of rolls being arranged at su'hstantia ly the point. where the edge normally moves inwardly of the sheet.

9.- In sheet glass apparatus, means for drawing a sheet from a mass of molten glass, pairs of rolls-arranged at each edge of the sheet and engaging the same, the lower pair of rolls being arranged at the formative portion of the edge, and the upper pair of rolls being arranged at substantially the point wherg the edge normally moves inwardly of the sheet, and means for driving the upper rolls in a manner that they will have *a relatively greater peripheral speed than the lower rolls.

10. In sheet glass apparatus, means for drawing a sheet from a mass of molten glass, pairs of rolls arranged at each edge of the sheet and engaging the same, the lower pair of rolls being arranged at the formative portion of the edge. and the upper pair of rolls being arranged at substantially the point where the edge normally moves inwardly of the sheet, and means for controlling the temperature of said rolls.

11. In sheet glass apparatus, means for drawing a sheet from a mass of molten glass, upper and lower rolls arranged at each edge of the sheet and engaging the same, the upper roll having a peripheral speed relatively greater than that of the lower roll.

12. In sheet glass apparatus, means for drawing a sheet from a mass of molten glass, upper and lower rolls arranged at each edge of the sheet and engaging the same, and means for retarding both rolls in a manner that their peripheral speeds will be different.

13. In sheet glass apparatus, means for drawing a sheet from a mass of molten glass, upper and lower rolls arranged at each edge of the sheet and engaging the same, the lower roll being arranged at the formative portion of the edge and the upper roll being arranged at substantially the point where the edge normally moves inwardly of the sheet.

14. In sheet glass apparatus, means for d awing a sheet from a mass of molten glass, upper and lower rolls arranged at each edge of the sheet and engaging the same, the lower roll being arranged at the formative portion of the edge and the upper roll being arranged at substantially the oint where the edge normally moves inwar ly of the sheet, and means for driving the upper roll in the inseam manner that it will have a peripheral speed relatively greater than that of the lower roll.

15. In sheet glass apparatus, means for drawing a sheet from a mass of molten glass, a rotatable bending member for deflecting said sheet from one plane to another, a plurality of pairs of rolls arranged at each edge of the sheet and engaging the same, the pair of rolls adjacent the bending member being driven at a speed intermediate the speed of the said bending member and the other rolls.

16. In sheet glass apparatus, means for drawing a sheet from a mass 0]": molten glass, a rotatable bending member for deflecting said sheet from one plane to another, upper and lower pairs of rolls arranged at each edge of the sheet and engaging the same, the upper rolls being driven at a speed intermediate the speed of the lower rolls and bending member.

17. In sheet glass apparatus means for drawing a sheet from a mass of molten glass, a rotatable bending member for deflecting said sheet from one plane toanother, upper and lower pairs of rolls arranged at each edge of the sheet and engaging the same, and means for retarding the pairs of rolls in a manner that the peripheral speed of the upper rolls will be relatively greater than that ol the lower rolls and relatively less than that of the bending member.

18. In sheet glass apparatus, means for drawing a sheet from a mass of molten glass, a rotatable bending member for deflecting said sheet from one plane to another, upper and lower pairs of rolls arranged at each edge of the sheet and engaging the same, the lower rolls being arranged at the forma-" tive portion of the edge and the upper rolls being arranged at substantiallv the point where the edge normally moves inwardly of the sheet, and means for driving the upper rolls in a manner that they will have a relatively greater peripheral speed than that of the lower rolls and relatively less peripheral speed than the bending member.

Signed at Charleston. in the county of lianawha and State of V'Vest Virginia, this 10th day of May, 1924.

JOHN L. DRAKE. 

